nemecsek



. Aug. 18, 19,59 1 ,.1. NEMEcsEK 2,899,908

EJECTOR POTS Filed July s, 195e 4 sheets-sheet 1 Z2 I y.

6,5 ATTORNEY Aug. 18, 1959 L. J. NEMEcsr-K EJECTOR POTS Filed July 5, 1956 4 Sheets-Sheet 2 Aug. 18, 1959 L. J. vNEMECSEK I 2,899,908

EJECTOR POTS BY @JQ-,WM

/7/3 ATTORNEY Aug. 18, 1959 1 J. ANL-:MECSEK 2,399,908

lEJECTQR PoTs Filed July 5, 1956 4 sheets-sheet 4 l: /l l ij/ 420@ #520 y 24 6'?? we @if Q2 621 J 7&1

-f 65M a @-v' f 724 L/y.

I 3?0 lNvENToR A i 827 zzzfj /V'mf'rfe 834 840 'BY gil-VM ATTORNEY 2,899,908 Patented Aug. 18, 1959 nited lStates PatentI ce EJEQTOR Pors Louis I. Nemecsek, Bergenfield, N .J assignor to Ralph B. Carter Company, Hackensack, NJ., a corporation of New Jersey Application -July 5, `1956, Serial No. 595,924

13 Claims. (Cl. 10S-243) This invention relates to pneumatic sewage. ejeotors, and more particularly to automatic weight-actuated systems of this character.

A pneumatic ejector is a device which pumps the liquids from a receiver o1'. pot onto a higher level by the use .of compressed gas which displaces the liquid in the receiver. As the receiver collects the raw liquid sewage by normal gravity feed through a check valve in the inlet line, the liquid level in the receiver rises -to a predetermined maximum. A control element then causes the closing of a valve in the conduit which connects the .interior of the receiver with the atmosphere and introduces ,compressed gas to force the. liquid .sewage through a second check valve into. the discharge line until the sewage in .the receiver reaches a predetermined 10W level, whereupon the control element shuts off thesupply .of compressed gas and `again opens .the vent. The control elements of known construction for the above purpose are actuated` mechanically or electrically, and lare `at least partially mounted in the receiver in contact with the raw liquid sewage.

The best known control v elements employed in the prior ejector pot systems are ,(a) the float arrangement and ,(b) stationary type probe cletrodes. Since the ejector pot handles raw `sewage with a relatively vhigh-solids content, the activating devices inthe receiver often become clogged or fouled and .thus require frequent lrepairs and replacement of parts; necessitating cumbersome .opt-.fling f the receiver.

Tho proscrit invention provides ,a pncumatic .cicctor which is equipped with .control-elements cxtcrucl .to the receiver.

The invention further provides an ejeCIQr of theabove character wherein the control elements are not incontact with the liquid sewage..

Still further', the invention 7provides a pneumatic ejector which operates automatically, it being actuated by the static force. of the liquid sewage accumulated vin .the receiver.

Yet further, the invention provides a Vcontrol system for lthe pneumatic sewage ejectors which is Vs irnple inconstnuction and requires a negligible tilting vI noveinent ofthe receiver.

The inventionalso provides a novel liquid-tight flexible coupling between the supply and discharge lines on the one hand, and the tiltableV recevier on Ythe otherhand:

A more specific feature of the invention resides in the provision of a simple and eicient device responsive to the changes in the voverall weight of the ejector potwhich actuates the control .elements ,and causes intermittent automatic ejection of sewageifrorndthe receiver.

The i present invention falso solves fthe problem of v,counteractingor-neutralizing the dynamic forces acting onthe weighing device which are. due to .the provision 4of exble couplings between the receiver and the `rigid connecting .piping- 'lhe invention resides essentiallyin the provision `,of a

tiltable receiver. whichfmay.bcinclincd.independently .of

the sewage piping and of the gas inlet and outlet conduits; .and in the provision of an cjcctor system. rcsponsivcto a predetermined minimum ory maximum ovcrall weight of thc. rcccivcr. inclusive .of its. contcrits, acting on a suitable weighing device, the latter being connected with control cit-.ciaooo .for introduction of rcw Sou/asc and compressed gaps. The dynamic forces une to the inability of the refceiver are compensated for byproper select-ion of the diarneter o f the llexible couplings and by suitable arrange,- mont ct .Such couplings with .fcsrcct to thc pvot Points or dead legs of the receiver.

Other features and advantages of :the novel automatic system will become apparent the lcourse of the follow.- ing .description of some preferred `emboc'liments which are illustrated inthe accompanying drawing', andthe inventiouwill be malls/routed our 'in the appended claims.'

In the drawing, Y 'i Fig. 1 is a side elevational View, P ally in section, of .one ctnbcoimcnt .of thc weight-actuated automatic .ciccto PO;

Fig. lq is .an .Qll-fgcd .detail view of the Aflexible liquid seal;

,Fis .2. .is .c .horizontal Sccticu taken on 1 inc 2,-2 in Fig- A1, a, s"viewed in the direction of arrows; M

Fig 3 is an end view of 1 .Fie 3c is cn .onlcrgcd Scctional. Yiciv Aof thc weighing device, ltalcen on linez-Sgz in Fig, Il, as viewed the direction ot arrows; i

Fig.- b illustrates thc .cir veut valve for .thc rcccivcr;

Fic 4 is .a .vertical .Scctiou :tatoo on .liuc 5&4 in.' .F i6, sttovius c dicfont .embodiment of .thc ilu/cotton;

' FigffS is a section talenon line 5.-15 in Fig. l6;

Fig-.61S a tcp pieu uicw of thc ucvicc Showu in Fisc- .4 and 5.; and

-Figs. 7 `to 24 are schematic representations of anlejecto'r potfeach figure lshowing a different positioning of tl'ie weighing device, of the pivots, of the conduit'for compressed' gas, and of the sewage inlet and outlet The weighing device cooperating with theliveileg of the receiver 'will be hereinafter referred to as the load Cell.

n Referring now in Vmore detail to the illustrated embodiments, andtirst to Figs. Ito/3d, thereis Wslownma receiver 20 of known size'and shape which i's'conneicted with the sewage and compressed "gas'piping by llexible members permitting na limited tilting movement thereof. Flexible coupling 21 connects the `ieceiverv`h2`0 with the Aline 22 which leads to'a gas compressor 55 alternately connects'ithe receiver with the atmosphere. A liquid coupling, generally indicated by numeral 23, and shown in more detail Fig. la, llexibly connects the lower end of the receiver 20 with yas ewage line 24, 'the receiver being supported at three points, to wit: byknife .edges at 25,26, and by a point support at 2.7.V As seenin Fig. 2', the .knife edgesZS, 26 are in a line to form the liquid-tight seal between the receiver 20 and the sewage .Rigid dead legs 34, 35, depending from the receiver 20, arie suitably shaped at their lower .extremities to receive the lgnifeedges 25, 426 of a supporting bracket 3 6, the

-latter-bein'g-fastenedto the Vground 38 at 37. A bracket 39 supports a load cell 40 receiving the static Vforce or weight ofthe receiver 20 through afliveleg A41.wi th the 'I Point2?, the live leg 41 being fastened tothe receiverJZil.

The sewage line 24 includes an inletsectionfaiidian outlet section 43, both sections being controlled by respective inlet and outlet valves (not shown).

In the preferred form, the load cell 40 consists of a body portion 44 in which a piston 45 transmits the .static force to the hydraulic fluid 46 through a diaphragm 47. The body assembly, including a small cylinder 44a and a large cylinder 44b, has an outlet 48 which is tapped to receive one terminal of the pilot line 49 leading to the pressure switch 50. The pressure switch 50 is provided with suitable terminals 51, 52 of the control circuit for the starter 53 of the compressor motor 54; it also controls the valve 22a in the conduit 22h connecting the receiver 20 with atmosphere. Conduit 22b communicates with line 22, as is shown in Fig. 3b, and the valve 22a installed therein is connected with line 22 by a bypass conduit 22C. When the compressor 55 is in operation, compressed air in lines 22 and 22e causes the valve 22a` to close conduit 22b, the compressed air owing into the receiver 20 to cause ejection of sewage accumulated therein. When the compressor is inactive, valve 22a automatically opens line 22b to atmosphere. Member 22a shown in Fig. 3b is a diaphragm valve of known construction.

"in will create a certain static force acting on the load cell 40 through the point 27 of the live leg 41, which force induces a proportional static hydraulic pressure in the pressure switch 50 via pilot line 49. The switch 50 then starts the compressor motor 54 which causes the compressor 55 to supply gas under pressure into the receiver 20 while also closing the air vent and the inlet valve in sewage line section 42, and opening the outlet valve in the section 43. As the liquid level in the receiver 20` descends, the combined weight of the receiver decreases until a lower liquid level is reached therein, as indicated by line B-B in Fig. l, whereupon the switch 50`shuts olf the starter 53 of the compressor motor 54. The outlet valve is closed at the same time, while the valves in section 42 of the sewage piping 24 and in the air vent reopen, permitting the liquid sewage to enter the receiver 20 by gravity flow and ll it up to the level vA-A, whereupon the above-described process is repeated in the same manner and sequence.

A particular advantage of the above system resides in that both the sewage inflow and ejection occur from vthe conical bottom of the receiver 20, which prevents the formation of residual sewage since, when the sewage is Y removed from the bottom of the receiver, the floating and settled materials will be discharged equally and no sedimentation is possible. l

A feature common to all embodiments of my inven 1 diaphragm being also attached to the sewage line 124 which,.outside of the receiver 120, branches into two sections 142, 143, with section 143 leading to the main members 136, 137 with its dead legs 134, 135, respectively, and on the left-hand end 153:1 of the arm 153 with its live leg 139. When the liquid sewage, entering through crum154 to lift its remote right-hand end 153b and make contact at 155 actuating a start relay (not shown) connected in the circuit of a compressor motor (not shown) to introduce compressed gas through a conduit 122 and a Hexible coupling member 121 above the liquid level into the receiver 120, and to expel the raw sewage into and through the pipes 124'and 143.

The rider 156 is at rest against the stop 157 on the arm 153, the latter also supporting a second stop 158 and a reversible motor 159. The start relay connected with the contact 155 also starts the motor 159 which causes the rider 156 to move along the bar 160 in the direction toward the stop 158. 'I'he motor 159 stops upon contact of rider 156 ,with theV stop 158. This stop 158 is so adjusted that the rider 156 becomes an effective counter- Weight against the combined weight of the receiver and the liquid contents at the stop level B-B thereof', plus the maximum dynamic back pressure multiplied bly the 'area of opening of diaphragm 133 (see diameter D).

The effective area of the diaphragm 133 must be kept yas small as possible as any variation in the pressure in the discharge main line will change the actual liquid ylevel when the arm 153 -drops to reach the contact 161 of a stop relay (not shown). When the contact is made at'161, the relay stops the compressor motor and starts 'the reversible motor 159 in a direction to return the rider 156 against the stop 157.

The same scale control maybe employed on units of diiferent sizes by varying the ratio x/y (see Fig. 6), where x is the distance between the axis of the receiver 120 and the knife edge supports 136, 137, and y is the distance between the axis of the receiver 1,20 and the i' pointed edge 127 of the live leg' 139.

tion is in that the ejector pot is controlled by its own weight and the weight of the liquid sewage accumulated .line (not shown), and section 142 introducing liquidV `sewage by gravity flow. The receiver 120 rests on rigid the line 142, reaches the level A--A (see Fig. 4), the

combined weight of the receiver and the raw sewage therein will cause the tilting of arm 153 around the fulaifect the load cell 240.

In Figs. 7 to 10, there is shown schematically a sewage receiver 220 combined with a load cell 240, the receiver being isolated from the external elements, such as piping and/ or rigid supporting members, and supported in static equilibrium by at lleast three point contacts, one of these contacts being between the' load cell 240 and the receiver 220. The load cell 240 actuates suitable devices for controlling the supply of compressed gas, as described above. Gas is introduced into the receiver 220 through the line 222 when the combined weight of the receiver plus its contents acting on the load cell 240 corresponds to a predetermined on setting of the control device. On the other hand, gas is free to escape from the receiver 220 when the weight of the receiver plus its contents resting on the live leg 227 in contact with the load cell 240 corresponds to a predetermined ol setting of the control element.

In Figs. 7 to 10, the dead legs 234, 235 are in alignment, only the leg 234 being visible. In Fig. 7, the ilexible coupling 223e is in the horizontal portion of the tube 224a and the flexible portion 221a of the gas conduit 222a is in alignment with the vertical axis of the receiver 220a.

Fig'. 8 shows an arrangement similar to that of Figs. l to 3.a, excepting that theflexible gas coupling 221b is disposed in a horizontal conduit 222b whose end is coaxial with the receiver.

In Fig. 9, the flexible liquid coupling 223C is in a vertical extension of the tube 224C, whereas Fig. 10 shows the two dead legs 234d, 235d and the live leg 227d. extending radially from the upper portion of the receiver 220d. The pipe 224d extends coaxially into and close to the bottom of the receiver 220d in a manner similar to that shown in Figs. 4 to 6.

Figs. 7 to 10 also' show how the dynamic pressures The total force is equal to plus or minus the effecting force at'22l times the distance b, plus or minus the effecting force at'223 times the distance a, the sum .or the difference divided by c. Whether the resulting force affecting the load cell 240 is plus'or minus depends from theclockwise or counternecessary.

ciociwise orientation of the resultingmoments. Such resulting force .must be added to, .or subtracted from, the

static .force vacting on the cell .24.0.

VIf a dynamic condition arises, i.e., when there is a flow either to or from the receiver .caused by .unequal pressures between the statically isolated receiver and the rigid connecting piping, a `different concept .is approached since yexternal vforces caused .by these -unequal .pressures must be added to, .or subtracted from, the weight of the receiver ,and its contents. These forces will be equal to the sum of the effective areas of the connecting flexible members times the dierenceV `between Vthe atmospheric pressure and the .pressure at the exible connections. A receiver similar to those of Figs. l to 10 may be used. However, the controlling device or devices are .set to turn on when that portion of the sum of the vweight of the receiver plus -its desired contents affecting the load cell or cells, A.plus or minus any other forces created by the dynamic conditions affecting the load cell are equal to a predetermined setting. In other words, not only the weight of the receiver 220, plus the weight Aof the liquid sewage therein must be considered for determining the exact time of introduction of .compressed gas, but also all the` forces arising from the dynamic conditions and aiecting the load cell or cells 240. The .compressed gas will be released from Athe receiver 220 when the load cell '240 is acted upon by .the weight of the receiver, the weight of the liquid sewage therein at a predetermined lo'wermost level, eg. the level indicated by line 'B--B in Fig. 1, plus or minus any forces caused by the dynamic conditions affecting the load cell V240 at such lowermost llevel of the liquid sewage. The control element or elements actuated by the cell 240 will reach vthe predetermined off setting and after closing the supply of Acompressed gas to the receiver 220, Will connect the receiver with the atmosphere.

Figs. ll to l show a receiver 'pot 320 isolated by a `number of flexible connections which create lforces in opposing directions. As seenin Fi-gs. 1l to 14, the ilexible connections in the sewage and gas lines are disposed in pairs and arranged in a manner to create opposing forces `which cancel each other so that the load cell 340 is actually affected only by the weight of the receiver '320 and of ythe liquid sewage accumulated therein.

A comparison of Figs. 1'1 to 14 with Figs. 7 to l0 shows that the flexible connection 321 in gas conduit 322 is disposed symmetrically with respect to a exible coupling 321 which, in Figs. 1l, 12 and 14, is connected to the ground 33S. Similarly, in the embodiments illustrated in Figs. l1 and 12, a llexible coupling 323', connected to the ground 338, counteracts the flexible connection 323 in the sewage line 324. In Fig. 13, the exible members 321C, 321C and 323C, 323C are provided vbetween rigidly mounted portions of'respective lines 322e and 324C. Therefore, no connection tothe ground 338 is In Fig. 14, the flexible member 3211i' is grounded, but the members 323d'323d are between two rigidly mounted portions of line 3'24d and thus need not be grounded.

'In Fig. 1 5, ythe effective areas of 'flexible couplings 321e and 323e are equal to achieve the same result.

In Figs. 11 to 14, the eiective areas'of additional flexible couplings 321a321d' and 323a-323d are equal to the effective areas of necessary connections 321a- 321C! and 323a-323d. The *forces created by dynamic -pressures incouplings 321' and 323' are equal to, along the same lines, but in :directions opposed to the forces created at 321 and 323. The compressed gas -is introduced into the .receiver 320 when `theweight-of the receiver 320 vplus its contents at a predetermined maximum level, acting ona loadcell 340, plus or minus any other forces caused bythe dynamic conditions at..321 and 323, minus or plus the equal but oppositely directed forces caused by the kdynamic conditions at 321', 323', correspond to a predetermined on setting of the control` 6 .element .or elements. Similarly, .the control device will .shut oi the supply of gas .and connect the receiver with .the atmosphere when the load cell 340 is acted upon by the 4weight of the receiver, .the weight of the liquid sewage at the predetermined minimum level, and any forces induced by the dynamic conditions, will correspond to a predetermined off setting. '-Hence, the dynamically induced forces are not eliminated `but their effect on the load cell 340 is simply neutralized. As to Fig. 15, it will vbe apparent that the induced forces at 321e and 323e, acting along the same line but in opposed directions, will neutralize their effects on the load cell 349e.

In Figs. 16 to 20, the forces generated by the dynamic conditions intersect one another in the line connecting the contact points of the receivers 42ml-420e with dead legs 434a-434e and 435a-435e. The vforces created by the dynamic conditions are not eliminated, but their effect on the load cells 440a--440e is neutralized. The ilexible connections 42m-421e, 423a-423e are disposed so that the forces created 'by the dynamic conditions act in lines passing through any supporting point or points not containing a load cell 440. The forces created by dynamic pressures -will be counteracted by equal but oppositely directed static forces through support points other than those containing the load cell or cells 44th-440e. This dynamic condition can now be treated yas a static condition at the live legs in contact with the load cell `or -cells yMila-440e. Similarly to the principle of Figs. 1l tol l5, the dynamically induced forces are not eliminated, but simply neutralized by lequal oppositely directed forces.

'In Fig. 21, the concepts of Figs. 1l to 15 and of Figs. 16 -to 20 are combined in `that the line of forces generated at connection S23 passes through the dead leg 534, whereas the flexible connection 521 in gas line .522 is compensated for by a flexible coupling 521 attached to vthe ground 533.

In Fig. 22, the ,arrangement .of the ilexible connections 621 and 623 .is such that .the :back pressure affecting the weighing device or load .cell 640 creates a clockwise moment around the point 634, whereas the dynamic pressure at 623 is nulliiied by passing .through the point 634.

In Fig. 23, aclockwise moment around the point 734 created by the back vpressure can be rachieved by making the effective area lat 721 greater than the elective area at the coupling 723.

Finally, in Fig. 24, the forces created at the couplings 821 and S23 are in the same direction and will autoh matically create a clockwise moment around the point 834.

In Figs. 22 to 24, the release of gases Yfrom the receiver is effected by varying forces created by varying dynamic 'back pressures during the ejection cycle. This may `be effected by reducing or destroying the dynamic back `pressure in therigid portion of the discharge piping by displacing the liquid vin this line with the gas from the receiver in any of the following possible manners:

(a) Through a throttling device which creates a dynamic pressure against the viscous liquid but not .against the gas. This throttling may be created by a section 4of the discharge line itself, and may .be .destroyed when the liquid vreaches aline of greater diameter or a chamber.

(b) By reducing the Weight of the liquid in va vertical rise in the discharge piping. In this case, the gas sustains the momentum of the .liquid up the pipe by pushing `it from the bottom.

(c) By the gas escaping to the atmosphere when displacing all of the liquid inthe line.

As a further modification, the proportioning of the eftective areas of the ilexible coupling employed to isolate 'the receiver from the rigid connecting piping may be made such that the sum of moments created by the elective dynamic pressures around a line pasisng through two dead legs will-be equal zero. Thismay be successfully applied, for example, inthe arrangement of Figs. '7, `9 and 10,

Whether the control devices are, or are not, calibrated to consider the forces created by the dynamic conditions, it will be seen that all the described embodiments follow the principle that externally located elements are made responsive to the weight of the receiver and its contents to introduce the compressed gas into the receiver, or release the gas therefrom after all or the desired amounts of liquid sewage had been ejected.

For the sake of simplicity, the receiver has been described and shown as having only two dead legs and one live leg acting on a single weighing device. It will be understood, however, that three or more dead legs could be aligned and two or more weighing devices or load cells associated with an equal number of live legs to achieve the same results.

It is also possible, especially in existing ejector pots, to connect a relatively small tiltable supplemental container with the rigidly mounted receiver by flexible connecting piping, and to provide one or more load cells below the corresponding number of live legs of such a supplemental container. This tiltable container communicates with the stationary ejector pot and the liquid level of raw sewage is therefore equal in both at all times. The pressure switch is responsive to the combined weight of the tiltable supplemental container plus the liquid contents thereof, and actuates the previously described inlet and outlet valves, the compressor motor, and also controls the air vent.

Various lfurther modifications in constructional details and in the arrangement of parts will occur to persons skilled in the art within the spirit of my invention, and I therefore do not desire to be limited to the exact details of the foregoing description, but only by the scope of the appended claims.

I claim:

l. A sewage ejecting apparatus comprising, in combination: a sewage receiver; three supporting legs for said receiver so disposed in a triangle that the receiver is tiltable on two of said legs about a horizontal axis; piping connected with the receiver for introducing sewage into and `for leading sewage out of said receiver; a source of compressed gas; conduit means in communication with said receiver and connected with said source; exible coupling means disposed between said piping and said receiver, and between said conduit means and said receiver, respectively, for permitting displacements of the receiver relative to said piping and said conduit means; a weighing device disposed beneath the third of said legs and having continuous supporting contact therewith, said weighing device com- 'prising means for conveying pressures generated by the combined weight of said receiver and its contents acting upon said last mentioned leg; and actuating means operatively connected with said weighing device through said last mentioned means and with said source for causing ow of a compressed gas from said source through said conduit means into said receiver throughout a fixed pressure range generated by the combined weight of the receiver and its contents acting upon said last mentioned leg and said weighing device.

2. The combination according to claim l, wherein yeach of the two rst mentioned legs on which said receiver is tiltable comprises two members fixed to the ground and to` the receiver, respectively, each member having a yfree extremity, the free extremity of one member defining a knife edge `engaging with the free extremity of the other member, the knife edges being aligned with one another and said horizontal axis passing through the points of contact between said members.

3. The combination according to claim 1', wherein said `weighing device further comprises a cylinder; vertically disposed piston means Vin saidV cylinder having an upper end in contact with said last'mentioned leg; a Vdiaphragm in said cylinder. connected with said piston means ,and

having an underside; and tubular means connected with "a said cylinderand with said actuating means-respectively, for providinga'communicationfbetween said cylinder and said actuating means,'sa1d means for conveying pressures being a hydraulic uid lling said tubular means and said cylinder andjin Vcontact with the underside of said diaphragm.

4. The combination -according to claim 3, wherein said actuating means is a pressure switch and said source of compressed gas is a compressor having a motor and starting means therefor and an electrical connection between s. id starting means and said .pressure switch.

5. The combination according to claim l, wherein said Weighing device comprises a support; an arm tiltably carried by said support for -movements about a horizontal axis, the arm having a first end at one side of the support in engagement with said last mentioned supporting leg, and a second end at the other side of said support and movable between two extreme positions in response to variations in pressures conveyed by the last mentioned supporting leg to said first end; said source of compressed gas comprising a compressor and electric starting means therefor; and said actuating means comprising a pair of electric contacts in the circuit of Said starting means and so disposed with respect to the second end of said arm as to close said circuit when the second end is in one extreme position in response to increasing pressures conveyed to said tirst end, and to open said circuit when the iirst end is in the other extreme position.

6. The combination according to claim 5, further comprising a counterweight slidably carried by said arm; a pair of stops between said support and the second end of said arm and in the path of said counterweight for limiting the movements thereof; and a reversible electric motor for said counterweight electrically connected with said contacts in such a way as to move said counterweight toward the support when the second end of said arm is in the iirst mentioned extreme position, and to move said counterweight toward the second end of said arm when the latter is in the last mentioned extreme position.

7. The combination according to claim l, wherein said piping comprises an inlet pipe; a discharge pipe; and a common tube communicating with said inlet pipe, with said discharge pipe, and with said receiver, respectively.

8. The combination according to claim 7, wherein said irst mentioned `coupling means comprises a tubular element in said common tube, and further comprising a exible `connection between said common tube and the ground.

9. The combination according to claim 7, wherein said last mentioned coupling means comprises a tubular element in said conduit means, and said first mentioned coupling means comprises a first tubular element in said inlet pipe and a second tubular element in said discharge pipe, the apparatus further comprising a flexible connection between said conduit means and the ground.

10. The combination according to claim 7, wherein said receiver has a cover and said common tube extends through said cover and communicates withsaid receiver at a point close to the bottom thereof, said iirst mentioned coupling means consisting of a diaphragm sealingly connected with said cover and with said common tube, respectively. Y

11. The combination according to claim 7, wherein said receiver has a cover and said common tube and said conduit means are connected with said receiver through said cover.

12. The combination according to claim 7, wherein said receiver has a bottom and said common tube is connected with said receiver through said bottom, said first mentioned coupling means forming part of said common tube.

13. The combination according to claim 12, wherein said receiver comprises a cover and is of cylindrical 9 contour with a substantially vertical axis of symmetry, 1,600,504 said common tube and said conduit means being con- 1,828,206 nected with said receiver through the bottom and the cover, respectively, in line with said vertical axis.

References Cited in the le of this patent UNITED STATES PATENTS 1,411,585 Redmond Apr. 4, 1923 10 Halvorsen Sept. 21, 1926 Simmons Oct. 20, 1931 FOREIGN PATENTS Great Britain Feb. 6, 1952 

